class_docstr: A helper class that represents input string that to be modified.
  
  Text that Sample contains parsed in data set,
  ``TextField`` provides multiple methods for Sample to modify.
  
  Support sentence level and word level modification,
  default using word level API.
code: def get_word_case(word):
      if len(word) == 0:
          return "empty"
  
      if len(word) == 1 and word.isupper():
          return "capitalize"
  
      if word.isupper():
          return "upper"
      elif word.islower():
          return "lower"
      else:
          for i, c in enumerate(word):
              if i == 0:  # do not check first character
                  continue
              if c.isupper():
                  return "mixed"
  
          if word[0].isupper():
              return "capitalize"
          return "unknown"
  
imports: from .field import Field
  from ....common.utils.list_op import *
  from ....common.preprocess.en_processor import EnProcessor
  from ....common.settings import ORIGIN, TASK_MASK, MODIFIED_MASK
label_desc: Use image node_id 18 for calling the TextField obj's underlying member method code with example usage: obj.get_word_case(word) and returns: str, str, str, str, str, str, str